Post on 30-Jan-2016
Sensors for use in this class.
Sensors 2Robotics: Bridgewater state college.
Sensors for this class
● Now that we've covered sensors commonly used– Lets look at the sensors available for this class.
● We are using two robot controllers in this class– Handyboard
– Lego RCX
– Lego simpler but less powerful● Will use handyboard for first lab, Lego for second. Projects
as they come.
– Discuss sensors separately Handyboard today.
Handyboard
Photodiode (light sensor)● Omni-directional light
sensor– Low values for lots of light
– High values for little light.
– Make directional by wrapping in aluminum foil.
– Add two or three and can get direction information about light sources.
– Analog ports 2-6
IR reflectance sensor● IR reflectance
– “top hat”
– Active sensor emits IR radiation and detects it in same direction.
– “active range” (min range) of 2 cm; max range depends
– Point at nothing? Return high value; point at light colored close obj, return low value.
– Generally edge detection
– Black/white line following.
– Analog ports 2-6
IR Range Sensor (E.T head)
● IR Range sensor– Active sensor emits IR radiation and
reads the reflectance back.
– Effective range is 6-30 inches
● Objects farther away give lower return values. Closer to 6 inches gives higher return values.
● Closer than six inches and the return values decrease again
● Analog ports 16-20
Touch/contact Sensors
● Digital Sensors– Help simulate a sense of touch.
– 1 when pushed, 0 when not.
– Button: push button in.
– Lever switch: push on lever
● Very slight force required– Post switch, push in or sideways.
– Together primitive sense of touch
– actuator/effector limit switch.
– digital ports 7-15
Break-beam encoder
● Digital encoder sensor– Sends 1 when IR signal between
two poles is broken, else 0.
– Generally used as digital encoder ● Use gear or wheel with hole in it
to encode how many times the hole passes through the beams area.
– With software support can develop a speed/distance encoding.
– Encoder 0: digital port 7, encoder 1 digital port 8.
Handyboard sensors
● Selection of inexpensive analog and digital sensors– No soldering required
– Color, light and proximity detection
– Touch at a variety of distances from the robot● Lever very gentle, post fairly gentle.
– Encoder capable of recording how many times a particular act was done.
– Basic sensing with lots of potential.
Lego RCX Brick
Lego Light Sensor
● Lego light sensor– Enhanced light sensor
● LED emits small amount of light, then sensor detects light.
– Duel use● Point down: color detection● Point out: proximity detection.
– Return values 0-100● Some toolsets 1-100
Lego Touch Sensor
● Lego touch bump sensor– Basic on/off digital sensor
– Small bump area
– Use Lego pieces to provide a larger bumper for sensor.
Lego Temperature Sensor
● Temperature sensor– Thermometer
– Measures temperature in F or C
– Range from -20 to +70 C● -3 to +157 F
– Depending on language used, can get temperature in degrees, tenths, or raw values (0 to 1023).
Lego Rotation/Angle Sensor
● Rotation sensor– Gives rotation position and
counts rotations.
– Has resolution of 22.5 degrees (16 positions)
– Can record rotation either forward or backward.